Formerly true
But the Department of Homeland Security has changed all that.
All it takes is a declaration by the Secretary, presumably at the order of or after conferring with the President, that a crisis is an Incident of National Significance. Then they can walk in and coordinate everyone, right down to the locals. See the DHS site page on Emergencies and Disasters: Planning and Prevention, here. An excerpt:
The National Response Plan provides mechanisms for expedited and proactive Federal support to ensure critical life-saving assistance and incident containment capabilities are in place to respond quickly and efficiently to catastrophic incidents. These are high-impact, low-probability incidents, including natural disasters and terrorist attacks that result in extraordinary levels of mass casualties, damage, or disruption severely affecting the population, infrastructure, environment, economy, national morale, and/or government functions.
The destruction of a major city that is the principal ocean port of our largest river would be an Incident of National Significance, if only one were thinking of it in terms of using the government for the public welfare and the common defense, instead of trying to prove that we don't need it.